Background The role of nasal obstruction in the pathogenesis of obstructive sleep apnea/hypopnea syndrome (OSAHS) has been debated for decades. In this prospective study, we compared the pharyngeal aerodynamic characteristics of OSAHS patients and normal people, and investigated the contribution of total nasal airway resistance to the pathophysiology of OSAHS. Methods Computational fluid dynamics (CFD) was used to extract the average pressure and average airflow velocity in three transverse cross-sectional planes of the pharynx for statistical analysis, and the correlation between nasal resistance and the average pressure in the pharyngeal cavity was investigated. Results The negative pressure within the pharyngeal cavity was significantly higher in OSAHS patients than in normal subjects, and total nasal airway resistance correlated well with the average pressure in three consecutive transverse cross-sections of the pharyngeal cavity. Conclusions Greater negative pressure within the pharyngeal cavity contributed to the increased collapsibility of the pharynx in OSAHS patients, and the strong correlation between nasal resistance and pharyngeal pressure suggests that the nose plays a role in the pathogenesis of OSAHS. Chin Med J 2012;125(17):3039-3043